Have a friend? Is his/her birthday approaching? Want a giant cake for someone to jump out of? Excellent, here's some instructions for how such a cake was made for ewilhelm -- complete with some form of pyrotechnics, candles and decorations!

Video of the festivities on the final step...

Step 1: Materials and Dimentions

Don't be a square and do a circular stipper cake like everyone else -- make a square cake!

Ours has two tiers. The bottom tier being 3' square and about 2' tall and the top being 2' cubed.

To make such a cake you will need:

50' of .5" PVC pipe (you'll need about 42-45 feet of it).
8 orthogonal Tees
8 normal Tees

PVC saw (or other suitable device)

7 or so yards of fabric
3 cans of "Great Stuff" spray able expandable foam
Spray paints
Measuring Device

Zip Ties
Packing Tape
Fabric cutting device
Aluminum foil
Hot Glue would be nice
Butchers Paper (or other wide paper to cover the top)

6' of 2" PVC pipe (2' per candle)
1 confetti popper per candle
3' of string per candle

Step 2: Cut PVC

You will need:

.5" PVC:
16 2' lengths
02 3' lengths
08 6" lengths

1 6" length of PVC per candle

2" PVC

1 2' section per candle

Step 3: Assemble Frame

Assemble your PVC frame.

Start with the bottom tier. Start by connecting a 6" length to a tee. Then, connect a 2' length to the other side. Attach another tee to the end of the 2' length and finish up with another 6" piece on the other end of the tee. Do this 3 more times.

Attach 1 each orthogonal tee to 4 2' sections of PVC.

Now, attach a 3' length to one of the orthogonal tees (that has a 2' length already attached). Connect the other end of the pipe to another tee. Repeat this one more time with your other two tee/2' pipe pairs.

Finally, connect the orthogonal tee pairs with the first members you assembled. Don't forget the two extra ones in the middle (this will support the second tier).

Second Tier
Assemble the second tier by making a box just like you did with the bottom. Except this time, only use 2' lengths.

Final Frame assembly
Press the second tier into the bottom. It helps to flip the frame up side down.

Step 4: Make Frosting and Candles!

We have a few types of frosting. The main bits being long and wide strips to act as the top of the bottom tier and the other being the paper that will be where our friend jumps out of.

Great Frosting
Start my measuring how wide and long the top portion of your bottom tier is. Then, roll out some foil to this length and set outside. Liberally spray on some great stuff expandable foam to make a block of "frosting." It doesn't have to be thick - but it needs to completely cover the foil.

Allow this to cure -- then paint.Once the paint has dried -- rip off the foil.

Repeat this 3 more times -- measuring each time ;)

Edge frosting

Edge frosting is done by spraying long lines of foam onto foil -- allowing to cure -- then painting. Finish it off by tearing the foil away.

Top Frosting
No foam here -- just cut a sheet of butcher paper to fit on top - -then lightly paint to look like frosting. I found that keeping the can far away and misting the paper worked best.

Decoration
Make foam dots on foam -- then paint all sorts of funky colors to make stick on cake decorations.

Candle Flame
Stuff some foil down into the top of the 2" PVC. Then spray some foam inside. Allow it to cure -- then spray on more. The idea is to build up a block of foam that can be cut to look like a flame. Remember, it doesn't have to be perfect -- it just has to vaguely resemble a candle.

Step 5: Pyrotechnics

What better way to use our "half grain of pyrotechnic" confetti shooters?

First, tie a few feet of string to the end of your confetti party popper. Then, carve a hole for it in each candle flame. Guide the string through the hole and embed the popper into the cured foam. Be careful, now you have a loaded candle :p

Now is probably a good time to attach a 6" length of pvc to the bottom of your candle with zip ties. This will serve as a mount for later.

Step 6: Fabrics

Now it's time to wrap your cake. As this was a very temporary structure, our fastening method was packing tape.

Start off by taping fabric to a corner -- then drape around the cake, taping along the way. Once you've gotten back to that corner, cut off the excess and secure the loose ends with a little more tape.

Repeat for the top tier starting on the same corner (so you can hide it later).

Step 7: Final Assembly

So now we have a wrapped frame... Time to "cake-ify" it!

All of the little decorations you made earlier -- stick them on your cake... Randomly. Given the temporary nature of this cake, I used packing tape.

Next up -- attach the candles. For me, more packing tape -- but only because I forgot to bring zip ties. Tape, or zip tie the candle mount to the vertical supports on the top tier... If you want to be really fancy, you can add them on the bottom tier too. But I used three candles as my 2" PVC was recycled.

Next -- add your big frosting bits... Secure with more tape.

Then, attach your top tier paper. Secured with tape and cut to fit and interface with the candles.

Lastly -- add your edge icing. Really, if you have hot glue -- use it. These were especially delicate as there wasn't much surface for the tape to bond to.

Now, just tuck any extra fabric under the cake -- and it's done!

Step 8: Surprise!

Our cake was so big... we put two people inside. And on the subject of inside, it helps to have an "insider" -- someone to give you a heads up of when your target arrives so you can prepare (and get inside the cake).

It's also beneficial to not dwell with the cake there. As soon as your target arrives, have your group start singing happy birthday (or your song of choice) to help cue when to pull the poppers and jump out!

Hilarity will ensue. As we discovered, cakes are great for exiting... Not so great for entering.